The invention relates to an inlet system for an internal combustion engine, and internal combustion engine system and a vehicle.
The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described with respect to a heavy-duty vehicle, the invention is not restricted to this particular vehicle, but may also be used in other vehicles such as a car.
In internal combustion engine systems, e.g. for heavy duty vehicles, water may form due to condensation, which water may accumulate and cause problems to the operation of the system. EP1391677 describes a charge air cooler with a condensate outlet opening which is connected to an upstream side of an air charger. However, there is a desire to further reduce possibilities of problems caused by liquid formation in an internal combustion engine system.
It is desirable to reduce risks of problems in internal combustion engine systems due to liquid formation. It is desirable also to improve the function of internal combustion engine inlet systems with fluid conduits leading to air inlets of the systems.
An aspect of the invention provides an inlet system for an internal combustion engine, comprising
a compressor comprising a rotor, and
an air guide arranged to guide an air flow from an air inlet to at least one cylinder of the engine via the compressor,
characterized in that the inlet system comprises at least two fluid sources, and at least two fluid guiding elements each arranged to guide a fluid from a respective of the fluid sources to the air guide, between the air inlet and an outlet of the compressor,
that the fluid guiding elements present a first conduit for guiding a fluid from a first of the fluid sources, and a second conduit for guiding a fluid from a second of the fluid sources,
and that a restriction of a flow of the fluid from the first fluid source is provided by a downstream end of the first conduit and the rotor, whereby a downstream end of the second conduit is arranged so that a pressure drop provided by said restriction drives fluid through the second conduit towards the downstream end of the second conduit.
By providing at least two fluid guiding elements arranged to guide fluid from a respective of at least two fluid sources, the possibilities of reducing risks of liquid formation, e.g. due to condensation, causing operational problems is greatly reduced. By the fluid guiding elements being arranged to guide the fluid into the air guide, the water may be used for suppression of NOx formation during the engine operation. Where the engine system comprises a multi cylinder engine, the distribution of the fluid upstream of the compressor, or at least upstream of the outlet of the compressor, may provide an advantageous atomization of condensation liquid from various fluid sources for a better distribution between the engine cylinders.
It is understood that a first of fluid guiding elements may present the first conduit, and a second of fluid guiding elements may present the second conduit.
Said restriction will increase the local fluid speed and decrease the pressure at the end of the first conduit. This pressure drop drives fluid through the second conduit towards the downstream end of the second conduit. This is particularly advantageous where pressure at the first fluid source is relatively high, and the pressure at the second fluid source is relatively low. Thus, where the pressure in the second fluid source is insufficient to drive the fluid therefrom to the air guide, the flow from the first fluid source may be used to drive the flow from the second fluid source.
The downstream end of the second conduit being arranged so that the pressure drop provided by said restriction drives fluid through the second conduit towards the downstream end of the second conduit, does not exclude the fluid being simultaneously urged through the second conduit also by other phenomena, such as a suction of the compressor, or a relatively high pressure at the second fluid source. Thereby, the pressure drop provided by said restriction contributes to urging the fluid through the second conduit towards the downstream end of the second conduit. The fluid may however be urged through the second conduit due solely to the pressure drop provided by said restriction.
Thereby, a simple and reliable way of driving the fluid from both sources may be provided. This will reduce risks of problems in the engine due to liquid formation.
Preferably, the restriction is created by the first conduit downstream end being in a vicinity of the rotor. Thereby, a reduction of the cross-sectional area of the flow coming out of the first conduit, and thereby the pressure drop, may be secured. The restriction may be arranged so that a cross-sectional area of a flow through the restriction is smaller than a cross-sectional area of the flow in the first conduit upstream of the first conduit downstream end. This will ensure a local increase of the flow speed, providing the pressure drop for driving the flow through the second conduit.
Preferably, compared to the first conduit, the second conduit extends further downstream in the air guide. Thereby, the downstream end of the second conduit may be, compared to the downstream end of the first conduit, further downstream in the air guide. Preferably, the downstream end of the second conduit is in a vicinity of said restriction. Thereby, it may be ensured that the downstream end of the second conduit is arranged so that the pressure drop provided by said restriction drives fluid through the second conduit.
Preferably, the distance between the downstream end of the second conduit and the downstream end of the first conduit is within 0-30 mm, more preferably 0-20 mm, for example 0-10 mm, or 0-5 mm. Thereby, the distance between the first and second conduit downstream ends may be suitable for a variety of vehicle internal combustion engines, such as engines for heavy duty vehicles, e.g. trucks. The sizes of the engine may range e.g. from 2, 4, 7 or 10 liters, to 20, 17, or 15 liters. Beneficially, the second conduit downstream end is as close as possible to the restriction. It should be noted that the second conduit downstream end may be downstream or upstream of the first conduit downstream end, or at the same air guide longitudinal position. The second conduit downstream end may be in relation to the first conduit downstream end displaced laterally in the air guide.
At least two of the fluid guiding elements may form a conduit outlet arrangement for injecting fluid into the air guide, upstream of the outlet of the compressor. More specifically, the downstream ends of the first and second conduits may form a conduit outlet arrangement for injecting fluid into the air guide. In particularly advantageous embodiments, the conduit outlet arrangement is, as seen in a transverse cross-section of the air guide, centrally arranged in the air guide. The conduit outlet arrangement is preferably arranged to inject the fluid guided by said at least two of the fluid guiding elements towards the centre of the rotor. More specifically, the conduit outlet arrangement is preferably arranged to inject the fluid guided by said first and second conduits towards the centre of the rotor. It is understood that the rotational axis of the rotor may be parallel to the local air flow upstream of the compressor; e.g. as in a centrifugal compressor. The rotational axis of the rotor advantageously extends through the downstream end of the first conduit.
The conduit outlet arrangement may comprise one or more nozzles, ejectors or dispersion devices. For example, one or both of the first and second conduit downstream ends may comprise a nozzle, an ejector or a dispersion device. By the injection towards the centre of the rotor, the risk that water from said fluid sources will damage the rotor is minimized. More specifically, since the linear velocity of the inner rotor part is, due to a smaller radial distance from the centre of rotation, smaller than the velocity of the outer rotor part, the impact velocity of water droplets will be smaller closer to the centre of the rotor.
In some embodiments, the conduit outlet arrangement and the rotor are partly integrated. Thereby, a portion of the rotor may extend into the conduit outlet arrangement. Preferably, the conduit outlet arrangement is located upstream of a high pressure part of the compressor. Preferably, the conduit outlet arrangement is located upstream of a part of the compressor in which part the fluid(s) is/are fully compressed. The compressor may be a centrifugal compressor comprising the rotor onto which blades are mounted. Preferably, the conduit outlet arrangement is located upstream of the blades. By means of the integration, e.g. by a portion of the rotor extending into the conduit outlet arrangement, the restriction may be created between the end of the first conduit and the rotor.
In alternative embodiments, the first conduit may terminate upstream of the compressor rotor. Thereby, a portion of the rotor may present a diameter that is close to the inner diameter of the first conduit. As suggested, the downstream end of the first conduit may be relatively close to the rotor portion. Thereby, the restriction is created between the downstream end of the first conduit and the rotor. Similarly to the embodiment described above, this will increase the local fluid speed and decrease the pressure at the end of the fluid guiding element, whereby fluids transported by the fluid guiding element may be driven by a pressure difference between one or more fluid sources from which the fluids are transported and the end of the fluid guiding element, serving to drive the fluids towards the end of the fluid guiding element.
Preferably, at least a part of one of the first conduit is integrated with at least a part of the second conduit so as to form an integrated fluid guiding element. The integrated fluid guiding element may terminate at the air guide. The integrated fluid guiding element may present a conduit for guiding a fluid from one of the fluid sources as well as a fluid from another of the fluid sources. Thereby, fluids from a plurality of sources may advantageously be injected towards the centre of the rotor of the compressor.
The first and second conduits are preferably concentrically arranged. Advantageously, said first and second conduits are concentrically arranged at the conduit outlet arrangement. Thereby, fluid from two or more fluid sources may be guided separately up to the conduit outlet arrangement, but nevertheless both injected towards the centre of the rotor of the compressor. The second conduit may surround the first conduit, as seen in a cross-section which is perpendicular to the fluid flow direction. By a portion of the rotor extending into the second conduit, the restriction may be readily created between the downstream end of the first conduit and the rotor.
According to another aspect of the invention, an internal combustion engine is provided, comprising
a compressor, and
an air guide arranged to guide an air flow from an air inlet to at least one cylinder of the engine via the compressor,
characterized in that the inlet system comprises at least two fluid sources, and at least two fluid guiding elements each arranged to guide a fluid from a respective of the fluid sources to the air guide, between the air inlet and an outlet of the compressor,
and that the fluid sources are liquid sources, and the fluid guiding elements are each arranged to guide a liquid from a respective of the liquid sources to the air guide, between the air inlet and the outlet of the compressor.
Thus, the fluid guiding elements may each be arranged to guide a liquid from a respective of the liquid sources to the air guide. Thereby, removal of liquid, e.g. provided due to condensation, may be provided in an effective manner. Thereby the risk of operational problems is greatly reduced.
The inlet system may comprise a valve arranged to control the communication between one of the liquid sources and the air guide via one of the fluid guiding elements based on an amount of liquid upstream of the valve. In some embodiments, said valve may be a float valve, or an electrically actuated, electronically controlled valve as exemplified below.
Such a valve provides means for reliably emptying liquid from the fluid source in a controlled manner. For example, where the fluid source is a charge air cooler, the valve provides means for disallowing compressed gas, rather than water, out of the charge air cooler, and this will prevent a loss of compressor power due to the fluid guiding element providing the communication between the charge air cooler and the air guide upstream of the outlet of the compressor. Also, the pressure differential over the compressor may vary and become insufficient in some operating conditions for driving water out of the cooler to the air guide upstream of the compressor. When this happens, a relatively large amount of water may accumulate in the cooler and then, upon a sudden change of operating conditions of engine, in systems without a communication between the cooler and the air guide via a fluid guiding element and without a valve for controlling the communication, the accumulated water could rush into the engine and cause undesirable effects. With the fluid guiding element and the valve it will be possible to avoid such large water accumulations.
Preferably, one of the fluid sources is a charge air cooler, the air guide being arranged to guide the air flow to the at least one cylinder via the charge air cooler, the charge air cooler being located downstream of the compressor. Thereby a condensed water delivery system may advantageously be provided, transporting water condensing in the charge air cooler up to the engine intake for suppression of NOx formation. The embodiment provides simple means of water delivery to engine intake by utilising the available air pressure difference to drive the water from the charge air cooler to the air guide upstream of the outlet of the compressor.
In some embodiments, one of the fluid sources is a crankcase of the engine or is adapted to communicate with a crankcase of the engine. One of the fluid guiding elements may be a crankcase ventilation conduit for ventilating a crankcase of the engine. In further embodiments, one of the fluid sources may be an oil separator adapted to clean crankcase gas of the engine. The crankcase gas may include blow-by gases which during engine operation enter the crankcase from the combustion chambers of the engine. Where the engine has a relatively high amount of water in the combustion process, the blow-by gases may present a relatively high humidity. Thereby the gases transported to the air duct by the crankcase ventilation conduit will contain water which will be transported to the air duct. Thus, an effective removal of water from the crankcase is provided, while said water may be due to the transportation to the air guide advantageously used for reduction of NOx formation in the cylinders.
In some embodiments, one of the fluid sources is a condensation water trap which may trap condensation water in an exhaust gas recirculation conduit for the engine. One of the fluid guiding elements may form a part of an exhaust gas recirculation conduit for the engine. The fluid source, from which said one of the fluid guiding elements is arranged to guide a fluid, may be an exhaust gas cooler arranged to cool exhaust gases in the exhaust gas recirculation conduit. By including such a water trap and/or an exhaust gas cooler in the inlet system in said manner, condensation water in the exhaust gas recirculation conduit may be effectively trapped and removed and used in the engine operation for reduction of NOx formation. The condensation water trap may be arranged to trap condensation water in the exhaust gas recirculation conduit. E.g., the trap may be provided as a pocket in the conduit, adapted to collect or trap condensation water. Alternatively the condensation water trap may be an area of the exhaust gas recirculation conduit where condensed water tends to collect without said area having been particularly designed for it. E.g. the condensation water trap may be a conduit turn or bend in which condensation water accumulates due to gravity.
Preferably, the condensation water trap is located downstream of the exhaust gas cooler. The fluid guiding element arranged to guide fluid from the condensation water trap may be arranged to guide the fluid to a conduit outlet arrangement as described above. Thereby a pressure differential may be provided to effectuate such a transport of fluid.
The inlet system may comprise in addition to said one of the fluid guiding elements an exhaust gas recirculation bypass conduit arranged to: guide exhaust gases from the exhaust gas recirculation conduit to the air guide while bypassing a part of said one of the fluid guiding elements and terminating at the air guide. The exhaust gas recirculation bypass conduit is preferably less restrictive than the bypassed part of said one of the fluid guiding elements. The inlet system preferably comprises a valve for controlling the flow through the exhaust gas recirculation bypass conduit.
In operational circumstances where there is little or no water condensation in the exhaust recirculation conduit, and any water therein is provided in a vaporized form, said valve may be open so as to allow recirculated exhaust gases to pass through the bypass conduit. However, when there is a risk of substantial water condensation, e.g. during cold engine operations, the valve may be closed to force recirculated exhaust gases to the conduit outlet arrangement so as to direct the condensate water into the centre of the compressor rotor. In systems where portions of the exhaust gas recirculation conduit, including the exhaust gas cooler, are located below the compressor, e.g. due to space restrictions, a particularly large amount of water may accumulate in the cooler and in various conduit pockets and turns, and thereby guiding the water in said manner according to embodiments of the invention to the compressor rotor centre will be especially advantageous. As suggested, the bypassed part of said one of the fluid guiding elements may be more restrictive than the exhaust gas recirculation bypass conduit. This will facilitate allowing the conduit outlet arrangement to inject fluid towards the centre of the rotor. More specifically, a relatively restrictive conduit outlet arrangement will provide for concentrating the injected fluid towards the rotor centre.
It is understood that various combinations of fluid sources are possible within the scope of the invention. In particularly advantageous embodiments, one of the fluid sources is a charge air cooler, the air guide being arranged to guide the air flow to the at least one cylinder via the charge air cooler, the charge air cooler being located downstream of the compressor, and one of the fluid sources is a crankcase of the engine, is adapted to communicate with a crankcase of the engine, or is an oil separator adapted to clean crankcase gas of the engine. In further advantageous embodiments one of the fluid sources is a charge air cooler, and one of the fluid sources forms a part of an exhaust gas recirculation conduit for the engine. In some embodiments, one of the fluid sources is a charge air cooler, and one of the fluid sources is a condensation water trap which may trap condensation water in an exhaust gas recirculation conduit for the engine.
Preferably, at least a part of one of the fluid guiding elements is integrated with at least a part of another of the fluid guiding elements so as to form an integrated fluid guiding element. The integrated fluid guiding element may terminate at the air guide. The integrated fluid guiding element may present a conduit for guiding a fluid from one of the fluid sources as well as a fluid from another of the fluid sources. Thereby, fluids from a plurality of sources may advantageously be injected towards the centre of the rotor of the compressor.
In some embodiments, the integrated fluid guiding element presents a first conduit for guiding a fluid from one of the fluid sources, and a second conduit for guiding a fluid from another of the fluid sources. The first and second conduits are preferably concentrically arranged. Advantageously, said at least two fluid guiding elements are concentrically arranged at the conduit outlet arrangement. Thereby, fluid from two or more fluid sources may be guided separately up to the conduit outlet arrangement, but nevertheless both injected towards the centre of the rotor of the compressor.
An aspect of the invention provides an inlet system for an internal combustion engine, comprising
a compressor, and
an air guide arranged to guide an air flow from an air inlet to at least one cylinder of the engine via the compressor,
characterized in that the inlet system comprises a fluid source, and a fluid guiding element arranged to guide a fluid from the fluid source to the air guide, that the compressor comprises a rotor, that the inlet system comprises a conduit outlet arrangement for injecting fluid guided by the fluid guiding element into the air guide and towards the centre of the rotor, and that a restriction of a flow of the injected fluid is provided by the conduit outlet arrangement and the rotor.
Thus, a restriction of a flow of the injected fluid may be provided by the conduit outlet arrangement and the rotor, or a portion of the rotor. The restriction may be created between the end of the fluid guiding element and the rotor. The restriction may provide for the flow cross-sectional area to decrease at the end of the fluid guiding element or as the fluid leaves the fluid guiding element. This will increase the local fluid speed and decrease the pressure at the end of the fluid guiding element.
Said aspect of the invention may be provided in any embodiment described herein. Preferably, a portion of the rotor extends into the conduit outlet arrangement. Preferably, the conduit outlet arrangement is, as seen in a transverse cross-section of the air guide, centrally arranged in the air guide. It is understood that the inlet system in which a restriction of a flow of the injected fluid is provided as stated by the conduit outlet arrangement and the rotor may be combined with any suitable aspect or embodiment described herein.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.